[Артем Enot Грунин]

Используйте InstantiateTemplate Message

// Set up the CRM Service.
CrmService service = new CrmService();
service.Credentials = System.Net.CredentialCache.DefaultCredentials;

// Create a template instantiation request.
InstantiateTemplateRequest instTemplate =
new InstantiateTemplateRequest();

// The email template to use.
instTemplate.TemplateId =
new Guid("9AF74EF9-A04C-DA11-A0C5-000D9DD8CDAC");

// The object that this email is regarding.
instTemplate.ObjectId = new Guid("A0F2D8FE-6468-DA11-B748-000D9DD8CDAC");
instTemplate.ObjectType = EntityName.account.ToString();

//Uncomment this next line to return dynamic entities.
//instTemplate.ReturnDynamicEntities = true;

// Execute the request to create an email message from the template.
InstantiateTemplateResponse instTemplateResponse =
(InstantiateTemplateResponse)service.Execute(instTemplate);